Controversy has erupted over a decision to cover the French medieval walled city of Carcassonne in bright yellow circles in the name of art.

Dubbed "Concentric, eccentric", the project is the brainchild of contemporary Swiss artist Felice Varini, famed for creating illusions of flat graphics superimposed on three dimensional spaces via an eye-deceiving technique called anamorphosis.

Varini got local art students to attach thin aluminium strips painted yellow to the the fortress in southwestern France, a popular tourist destination which was fully restored in the 19th century, after projecting the circles on to its huge stone surface at night.

The artist was delighted with the work, officially inaugurated on May 4, as was the local town hall, which said it allowed people to see the fortress "in a new light".

It said it took the public on a "veritable aesthetic experience that enhances" their walking visit, as the yellow lines "spread out into the space like a wave".

But a group of locals were appalled at what they saw as an affront to the region's prized heritage.

A petition calling for the removal of the "filthy" artwork, has now gained more than 1,800 signatures.

One inhabitant told France Info radio: "The people of Carcassonne were not consulted. This is ruining our lives, because we have to look at it all day."